What differences between Dynaco PAT-4 and early PAT-5?

[[email protected]]

How is an early Dynaco PAT-5 pre-amp (not the FET version) different
from a PAT-4, aside from the fact that the PAT-5 has a speaker switch?

[Arny Krueger]

> wrote in message
ups.com...

> How is an early Dynaco PAT-5 pre-amp (not the FET version)
different
> from a PAT-4, aside from the fact that the PAT-5 has a
speaker switch?

If you find reading schematics a bit opaque...

The PAT-5 is based on 3 2-transistor single-ended amplifiers
and an integrated circuit operational amplifier, while the
PAT-4 is based on just 2 single-ended 2-transistor discrete
transistor amplifiers per channel.

[[email protected]]

Thanks for the info, guys. I note that the IMD and THD figures for the
PAT-4 are .05% and for the PAT-5 they are .007%, plus the PAT-5's noise
figure is 5 db. lower (-85 db. vs. -90 db.) on the line inputs. Do you
think these difference would be audible?

[Robert Morein]

> wrote in message
oups.com...
> Thanks for the info, guys. I note that the IMD and THD figures for the
> PAT-4 are .05% and for the PAT-5 they are .007%, plus the PAT-5's noise
> figure is 5 db. lower (-85 db. vs. -90 db.) on the line inputs. Do you
> think these difference would be audible?
>
IMHO, the PAT-4 is a pretty audible preamp. It is not quiet. The PAT-5
should be a little less obtrusive.

[Arny Krueger]

> wrote in message
oups.com...

> Thanks for the info, guys. I note that the IMD and THD
figures for the
> PAT-4 are .05% and for the PAT-5 they are .007%, plus the
PAT-5's noise
> figure is 5 db. lower (-85 db. vs. -90 db.) on the line
inputs. Do you
> think these difference would be audible?

Probably not. I have a PAT-5 that I picked up used, but no
PAT-4 so I can't advise about the comparison.

Frankly, with older equipment like this, how the switches
and potentiometers (volume control, etc.) work is far more
apparent than the electronics. Equipment this old needs to
be bench tested and recapped if low frequency response or
distortion are below par. Some transistors or ICs may also
have become leaky and noisy.

Dynaco had a bad reputation in the PAT-4 and PAT-5 era for
parts quality choices being made by accountants.

[Robert Morein]

"Arny Krueger" > wrote in message
...
>
> > wrote in message
> oups.com...
>
> > Thanks for the info, guys. I note that the IMD and THD
> figures for the
> > PAT-4 are .05% and for the PAT-5 they are .007%, plus the
> PAT-5's noise
> > figure is 5 db. lower (-85 db. vs. -90 db.) on the line
> inputs. Do you
> > think these difference would be audible?
>
> Probably not. I have a PAT-5 that I picked up used, but no
> PAT-4 so I can't advise about the comparison.
>
Regardless of the spec, I had a PAT-4, and it is a noisy beast.
David Hafler's fix for all this were the Hafler DH series preamps, of which
the DH-110 is spectacularly better.

[Fred]

"Robert Morein" > wrote in message
...
>
> > wrote in message
> oups.com...
>> Thanks for the info, guys. I note that the IMD and THD figures for the
>> PAT-4 are .05% and for the PAT-5 they are .007%, plus the PAT-5's noise
>> figure is 5 db. lower (-85 db. vs. -90 db.) on the line inputs. Do you
>> think these difference would be audible?
>>
> IMHO, the PAT-4 is a pretty audible preamp. It is not quiet. The PAT-5
> should be a little less obtrusive.
>
>

Was the preamps factory or kit? Don't know about the PAT-5 but I put
together the PAT-4 as a kit years ago and its quiet compared to any of the
source material at the time which is LP, tape, FM and AM. I don't think I be
able to hear the difference between 85 and 90 dB. To put this in
perspective, if I'm not mistaken, the McIntosh C2200 preamp has a S/N ratio
of 93 dB which isn't that much better than the Dynacos, in particular the
PAT-5, specification wise. Would the MaIntosh not quiet and obtrusive as
well?

[Robert Morein]

"Fred" > wrote in message
...
>
> "Robert Morein" > wrote in message
> ...
> >
> > > wrote in message
> > oups.com...
> >> Thanks for the info, guys. I note that the IMD and THD figures for the
> >> PAT-4 are .05% and for the PAT-5 they are .007%, plus the PAT-5's noise
> >> figure is 5 db. lower (-85 db. vs. -90 db.) on the line inputs. Do you
> >> think these difference would be audible?
> >>
> > IMHO, the PAT-4 is a pretty audible preamp. It is not quiet. The PAT-5
> > should be a little less obtrusive.
> >
> >
>
> Was the preamps factory or kit? Don't know about the PAT-5 but I put
> together the PAT-4 as a kit years ago and its quiet compared to any of the
> source material at the time which is LP, tape, FM and AM. I don't think I
be
> able to hear the difference between 85 and 90 dB. To put this in
> perspective, if I'm not mistaken, the McIntosh C2200 preamp has a S/N
ratio
> of 93 dB which isn't that much better than the Dynacos, in particular the
> PAT-5, specification wise. Would the MaIntosh not quiet and obtrusive as
> well?
>
It's been a long time. As I recall, it was almost inaudible, as you say, for
the media of the time. However CDs, and CD players, are quieter, and
benefit from a quieter preamp.